Economical in terms of human energy? Partly this (eg typing a long phrase when one shortcut would do?) but this is not it.

Or economical in a literal (monetary) sense? a bit of this, plus a third aspect

Did someone buy a brand new copy of an OS and perform a clean install? Or did they buy a brand new piece of hardware? Neither, this is in fact a stupidity puzzle that isn't computer related. Personal experience from my time in retail.

The item she bought - was it electronic? A food item? A treadmill? An item that could be only used once? Like a disposable camera? The thing or things she actually came in to the shop for, is not really relevant. But it might be food related. The shop I was working in was similar to a 7-Eleven, so convenience/grocery. There is something else going on here. Explore

Potato (Potato)

Did it turn out that whatever she bought wasn't what she actually wanted? Not this And she had to go back to return it to the store? She did return to the shop, but she didn't HAVE to.

Gregoryuconn (Gregoryuconn)

Did she buy some $10 item that was on sale for $7 and demand that you allow her to use her 15% off coupon, which would involve waiving the sale price and costing her $1.50 more? No, not this

Did she return it the item because in retrospect, she thought it was too expensive? And she went back to the store by car or public transportation which cost her more than the item was worth? Or more than she would've saved had she bought it somewhere else?

Did she return it because she didn't need it right away? Or because it was too much? Or too little? Did she realize that something was wrong with it? Did she start eating it and realized that she didn't like it? Was the reason why she returned the item a cogent one?

Did she return it the item because in retrospect, she thought it was too expensive? And she went back to the store by car or public transportation which cost her more than the item was worth? Or more than she would've saved had she bought it somewhere else?

Did she return it because she didn't need it right away? Or because it was too much? Or too little? Did she realize that something was wrong with it? Yes-ish, but I can smell a FA lurking in this line of questioning Did she start eating it and realized that she didn't like it? Was the reason why she returned the item a cogent one?

When she went back to the store, did she buy something else instead?

Did she return a regular pack of something in favor of an economy size one? No to rest

Was there any sort of sale or discount on the item? Did she bring back the item to be returned? To purchase again? Was there a discount for buying more than one? And she only bought one? So she brought that one back and bought a second one with it? But paid for the first one twice?

Was there any sort of sale or discount on the item? Did she bring back the item to be returned? To purchase again? Was there a discount for buying more than one? And she only bought one? So she brought that one back and bought a second one with it? But paid for the first one twice? She did bring it back. And no to all the rest.

HINT: There is something you still haven't found out, something important. The thing she returns is not really one of the 'items' she got in to the shop to buy. However, she paid for it and it was supplied to her from our shop. One other important factor - how did she get to the shop?

Walking? Bus? Taxi? Driving? Bicycle? Motorcycle? Train? Plane? (lol, I don't know, I suppose it depends on how far she was coming from) Did she buy the item from a catalog? And then go to the shop where it originated to return it?

Walking? Bus? Taxi? Driving? Bicycle? Motorcycle? Train? This is closest, it was the Metro/Underground.Plane? (lol, I don't know, I suppose it depends on how far she was coming from) Did she buy the item from a catalog? And then go to the shop where it originated to return it? No, not this.

The item she brought back - was it related to the Metro in any way? No it wasn't. I guess it could have worked with other varieties of public transport as well. And it is a spesific thing about the Metro, that adds to the time aspect of this.

Precise distance? General distance? This, compared to something Did she take the Metro when it would have been faster to walk? Or cheaper? Would have been cheaper to walk of course, but definitely not faster.

A customer entered the shop I was working in to buy a few things. Exactly what she purchased is not relevant. But there is a relevant item that she got from us, and that she paid for. She comes back a little later, to have this item replaced.

The stupid part is why and why she bothered coming back. To us it seemed to be a waste of time, and potentially money, to not gain anything whatsoever.

You need to find out what that item was, and why she wanted to exchange it.

HINT: When you go shopping and bring the items to the till to pay, what do you do with the items after you have paid?

She...tore a hole in the bag and needed it replaced? Hole and needed are HUUUUGE exaggerations, but it is enough for a

SPOILER

This regular customer (which to be honest alwasy behaved a bit weird) came in to our shop and bought a few things. In Norway you usually pay a small fee for plastic bags, normally around NOK 1 (€ 0.12) today, about half that back then. She asked for a plastic bag, which she paid for, packed her groceries and left, only to come back 10-12 minutes later.

She claimed she wanted a new bag, as the one she had, had a tiny hole in it. It was the tiniest tear on the upper half. Of course we replaced it. But she had gotten all the way down to the platform, waiting for the metro and then decided to walk back to get a new bag. As she said 'just in case the hole gets bigger, and then everything will fall out'.

The really stupid thing is that she lost her train, maybe even have to pay a new ticket (depending on circumstances), while the trip from her own station and home, would not have been any longer than the trip back to the shop.